1. Field of the Invention
This invention relates to buried-heterostructure lasers with buried optical guide which produce high outputs and which facilitate stable oscillations in fundamental modes.
2. Description of the Prior Art
As a semiconductor laser of high output, there is an example in which an optical guide layer is introduced in adjacency to an active layer in a double-heterostructure. It is, for instance, a semiconductor laser of a GaAs-GaAlAs heterostructure wherein one layer of GaAs is interposed between two layers of GaAlAs, the GaAs layer forms the PN-junction of the laser, at least one layer in the GaAlAs layers is an inner layer, and the inner layer is overlaid with an outer layer of GaAlAs having a greater mole fraction of AlAs than the inner layer. Examples of this type of semiconductor laser are disclosed in the official gazette of Japanese Laid-open Patent Application No. 47-8472; `Appl. Phys. Lett.`, 35(7), 1 October, 1979, pp. 513-516; etc. The semiconductor laser of this type has a structure in which photons and carriers are confined between different semiconductor layers.